<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src='./test.js'></script>
</head>
<body>
    <h1 style="color: red;">
        哈哈哈
    </h1>
    <!-- 默认： js的执行会则色页面渲染
         async：js的执行不会阻塞页面渲染
         defer：js的执行会阻塞页面渲染 -->
</body>
</html>